Gas piping connection for transformers



Feb, 11,1958 J. c. DUTTON v ,8

- GAS PIPING CONNECTION FOR TRANSFORMERS Filed Sept. 28, 1954 GAS PIPING CONNECTION FOR TRANSFORMERS fohn C. Button, Rome, Ga., assignor to General Electric Company, a corporation of New York Application September 28, 1954, Serial No. 458,923

4 Claims. (Cl. 174-14) This invention relates to gas piping connections and more particularly to improvement in such connections to a gas space in insulating liquid immersed transformers.

Insulating liquid immersed transformers of the nonconservator type are normally only partially filled with liquid and there is a space in the tank above the liquid level which is normally filled with gas which acts as a cushion to allow expansion and contraction of the liquid under varying conditions of transformer load and ambient temperature. it is often desirable to provide a pipe connection between the gas space and auxiliary apparatus such as a pressure-vacuum bleeder device, a gas-oil-seal tank or automatic gas pressure equipment.

Heretofore such connections have been made from the top side of the transformer cover and they have numerous disadvantages among which are high cost due to the amount of material involved, poor appearance, exposure to mechanical damage in handling or maintaining the transformer, necessity for breaking the connection when the cover is removed, likelihood of liquid entering the piping under operating conditions accompanied by high liquid level or due to splash of liquid during shipment of the transformer.

In accordance with this invention, there is provided a novel and simple pipe connection which is characterized by being mounted under the cover flange of the trans A further object of the invention is to provide a low cost virtually liquid and splash-proof gas piping connection for liquid immersed transformers.

The invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

Referring now to the single figure of the drawing, which is a broken away partly sectioned elevation view of a preferred embodiment of the invention, there is shown a transformer tank side wall 1 terminating at its upper end or rim in an outwardly extending cover flange 2 on which is seated a transformer tank cover 3. The flange 2 and the cover 3 may be fastened together in any suitable manner, such for example as by a welded joint which is indicated at 4.. Partially filling the tank is an insulating liquid 5 which may also act as a coolant. Any

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suitable type of liquid may be used, such as mineral oil or askarel. Above the level of the liquid 5 is a gas cushion space 6.

The portion of the tank wall 1 above the level of the liquid 5 is provided with two generally laterally adjacent vertically spaced openings 7 and 8. Opening 7 is mounted as close to the top of the tank as possible and still not be closed or sealed by the cover 3. Opening 8 is below the opening 7 and above the normal level of the liquid 5'.

The principal element of the gas piping connection comprises a block 9 of steel or other suitable metal mounted under the cover flange 2 and against the side wall 1 over the openings '7 and 8 therein. The block may be attached to the transformer tank in any suitable manner such as by a weld 10 which runs around the edges of the block 9 where they contact the cover flange 2 and the side wall 1 so as to provide a tight seal. Running from top to bottom, preferably vertically, through the block 9 is a passageway shaped roughly like an hourglass or a dumbbell in that it has a reduced diameter intermediate portion 11 and enlarged upper and lower portions 12 and 13 respectively. The enlarged upper portion 12 is a sump cavity and preferably has downwardly and inwardly tapering bottom surfaces 14 to facilitate liquid drainage. The lower enlarged portion 13 is internally threaded at 15 and preferably has an upwardly and inwardly tapering top wall 16 which forms part of a gland seal to be described in more detail hereafter.

An upper lateral passageway 17 in the block 9 extends along the underside of the cover flange 2 and serves to interconnect the top opening 7 with the top of the sump cavity 12. Actually the passageway 17 may be a groove in the top of the block 9, if desired. A second or lower lateral passageway 18 in the block 9 extends between the lower opening 8 in the tank wall and the wall of the reduced diameter intermediate portion 11 of the vertical passageway in the block 9. Passageway 17 is preferably restricted in comparison with passageway 18 so as to retard the flow of liquid therethrough.

A pipe, such as a copper tube 19, is inserted in the vertical passageway and has an open upper end contiguous to the underside of the cover flange 2. Preferably the side wall of the pipe is notched, as at 20, so as to insure the flow of gas if the top end of the pipe should accidentally be jammed tightly against the underside of the cover flange 2. The outside diameter of the pipe 19 is sufliciently less than the reduced diameter of the intermediate portion 11 of the vertical passageway so that there is a restricted passageway 21 between the bottom of the sump cavity 12 and the lower lateral passageway 18.

The pipe 19 is secured in position and the pipe connection is sealed against leakage by means of a resilient gasket 22 surrounding the pipe 19 in the lower enlarged portion 13 of the vertical passageway. A hollow externally threaded bushing 23 surrounds the pipe 19 and is screwed into the enlarged lower portion 13. Preferably a washer 24 is interposed between the end of the bushing 23 and the resilient gasket 22 so as to prevent twisting of or damage to the latter when the bushing 23 is screwed into place. This latter action compresses the gasket 22 against the tapered walls 16 and causes the gasket 22 to grip the side of the pipe 19 tightly thus holding the pipe in position and sealing the device against leakage. The lower end of the pipe 19 may be connected to any suitable apparatus such as a pressure-vacuum bleeder device 25, the details of which are not described as they form no part of the present invention.

The opening 7 is not necessary in all cases and can be omitted when there is little or no likelihood of gas pressure in the top of the tank forcing liquid up into the sump cavity 12 to a point where it overflows into pipe 19. Also the lower portion 13 of the vertical passageway need not in all cases be enlarged and the pipe 19 can be fastened therein in any suitable manner, such as by brazing or soldering.

The operation of the invention is as follows. Gas can flow in either direction between the space 6 and the inside of the pipe 19 through two parallel paths; the first is through the opening 7, the restricted passageway 17, the upper enlarged portion 12 and into the pipe 19; the second is through the opening d, the lower lateral passageway 18, the restricted passageway 21, the enlarged upper portion 12 and into the pipe 19. If the level of the liquid should rise above the opening 8, liquid will of course enter the lower lateral passageway 13 and although its flow will be retarded by the restricted passageway 21, it will seek its level in the upper enlarged portion or sump cavity 12. However, the upper lateral passageway 17 in cooperation with the upper opening '7 will allow equalizah'on of the pressure of the gas in the space 5 which is trapped in the tank above the opening ti and the pressure of the gas in the sump chamber 12 above the level of the liquid therein so that there can be no unbalance gas pressure built up in the top of the tank which could force liquid through the opening 8, the lower lateral passageway 18, the restricted passageway 21, up to the top of the sump cavity 12 and into the pipe 19. Of course, if the tank should become completely full of liquid, the level of the liquid in the sump cavity 12 will eventually overflow the top of the pipe 19, but this is an unlikely occurrence.

During shipment of the transformer, changes in its direction of motion will cause the liquid 5 to slosh around inside the tank. However, liquid entering the lateral passageway 18 through the opening will have difliculty in entering the sump cavity 12 due to the restricted passageway 21, but any liquid which does find its way into this cavity through such passageway will drain out again. Similarly liquid which finds its way into the upper lateral passageway 17 through opening 7 due to a splashing action will fall to the bottom of the sump cavity 12 and drain out through the restricted passageway 23, the lateral passageway 18 and the opening 8 back into the main tank.

While there has been shown and described a particular embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the invention and, therefore, it is aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a transformer tank having an outwardly flanged rim, a cover for said tank attached to said flanged rim, a quantity of insulating liquid in said tank having a normal level which is separat d from said cover by a gas space, a metal member attached to the underside of said flange rim, said member containing a liquid sump cavity, a lateral passageway between said gas space and said sump cavity connected so that liquid in said cavity flows through said passageway into said tank, a gas conduit from outside said extending upwardly into said sump cavity and having an open end within said cavity closely adjacent the bottom side of said flanged rim, and sealing means for preventing leakage of liquid from the bottom of said cavity along the outside of said conduit.

2. In combination, a transformer tank having an outwardly flanged rim, a cover for said tank attached to said flanged rim, a quantity of insulating liquid in said tank having a normal level which is separated from said cover by a gas space, a metal member attached to the underside of said flan ed rim, said member containing a liquid sump cavity, restricted lateral passageways between said gas space and the top and bottom of said sump cavity, the restricted passageway associated with the top of said sump cavity terminating at the inner side of said cover, the restricted passageway associated with the bottom of said sump cavity terminating at a lower level in said tank but above said normal liquid level so that liquid in said sump cavity flows into said tank, a straight gas conduit from outside said tank extending vertically into said sump cavity and having an open end within said cavity contiguous to the bottom side of said flanged rim, and sealing means for preventing leakage of liquid from the bottom of said sump cavity along the outside of said gas conduit.

3. In combination, a transformer tank partially filled with insulating liquid and having a gas space above said liquid, said tank having a side wall provided at its rim with an integral outwardly extending cover flange, a tank cover attached at its periphery to said cover flange, a pair of adjacent openings in said wall, an upper one of which is substantially at said cover flange and the other of which is at a lower level but above a normal level of said liquid, and liquid splash-proof means for making a gas piping connection to said gas space comprising a metal block covering said openings and attached to said tank wall and underside of said cover flange, a main passageway extending entirely through said block from top to bottom, said passageway having a reduced diameter intermediate portion between an enlarged upper portion and a lower portion, a first lateral passageway in said block extending between the enlarged upper portion of said main passageway and the upper opening in said tank wall, a second lateral passageway in said block extending between the reduced diameter intermediate portion of said main passageway and the lower opcring in said tank wall, a pipe extending into said main passageway and having an open upper end contiguous to the underside of said cover flange, the outer diameter of said pipe being sufiiciently less than the reduced diameter of the intermediate portion of said main passageway so as to form a restricted connection between the enlarged upper portion of said main passageway and said second lateral passageway, and means in said lower portion for making a fluid-tight seal with the outside of said pipe.

4. In combination, a steel transformer tank partially filled with insulating liquid and having a gas cushion above said liquid, said tank having a side wall provided at its rim with an integral outwardly extending cover flange, a tank cover attached at its periphery to said cover flange, a pair of adjacent openings in said wall, an upper one of which is substantially at said cover flange and the other of which is at a lower level but above a normal level of said liquid, and liquid splash-proof means for making a gas piping connection to said gas cushion comprising a steel block covering said openings and welded to said tank wall and to the underside of said cover flange, a vertical passageway extending entirely through said block, said passageway having a reduced diameter intermediate portion between enlarged upper and lower portions, the walls of said vertical passageway between the enlarged upper portion and the reduced diameter intermediate portion tapering downwardly and inwardly, the bore of the enlarged lower portion being internally threaded, the walls of said vertical passageway between the enlarged lower portion and the reduced diameter intermediate portion tapering upwardly and inwardly, a first restricted lateral passageway in said block extending along the underside of said cover flange between the top of the enlarged upper portion of said vertical passageway and the upper opening in said tank wall, a second and larger lateral passageway in said block extending between the reduced diameter intermediate portion of said vertical passageway and the lower opening in said tank wall, a pipe extending into said vertical passageway and having a notched open upper end contiguous to the under side of said cover flange, the outer diameter of said pipe being sufiiciently less than the reduced diameter of the intermediate portion of said vertical passageway so as to form a restricted connection between the enlarged upper portion of said vertical passageway and said second lateral passageway, a gasket surrounding said pipe in the enlarged lower portion of said vertical passageway, and an externally threaded bushing surrounding said pipe and screwed into said enlarged lower portion of said vertical passageway for compressing said gasket and sealing said pipe in said block.

References Cited in the file of this patent UNITED STATES PATENTS Hill et a1 July 9, 1929 Greenwood Oct. 11, 1932 St. Palley Oct. 18, 1932 Ford Aug. 4, 1942 Lennox Dec. 16, 1952 

